This is my buddy's 1970 1 ton. He converted it to 4wd a few years ago using a 3/4ton Dana 44 up front, NP205, and it's original Dana 60 dually rear. I recently gave him a Dana 70 dually rearend in exchange for some body work. I doubt he will ever go with a Dana 60 up front as it is not necessary for how he uses this truck. Chevy didn't make a 1 ton 4x4 in the 67-72 years, but Tony's sure turned out great.